For day to day planning such a forecast may not be useful but they are highly beneficial to people such as farmers who deal with the general growing season. These longer range forecasts often describe the forecast in departures from the normal weather (“the weather will be warmer and wetter than average”) rather than exact temperatures, rainfall etc. Longer term forecasts can also be found with time scales ranging multiple months into the future. The provider of the data then looks up the data for the cell you are requesting based off address (or latitude/longitude). These weather forecasts split the world into a grid of tiny squares and then calculate the weather at each point. The weather data is normally derived from ‘gridded’ models.

This depends on the organization that is calculating the forecast. The weather forecast is typically available for the coming 5–15 days. Some data providers provide historical data that is already processed so that they have historical records for nearly all global locations. In the latter case, the weather history at a particular point will be a an average of the nearby measurements. Historical records are collected by weather stations so typically we need to look up data by finding the closest weather station or a combination of nearby stations. Past weather records allow to identify the expected weather for the future

Weather underground historical weather